Since it opened in 2005, the Abraham Lincoln Presidential Library and Museum in Springfield, Ill., has consistently drawn more visitors than any other presidential museum in the nation. The place has averaged more than 400,000 visitors a year.

While Lincoln's has prospered, some other presidential museums haven't fared so well over the past few years, according to attendance figures from the National Archives. Attendance at the William J. Clinton Presidential Library and Museum in Little Rock, Ark., is down nearly 50 percent from its first year. The museum drew 233,345 visitors in the last fiscal year, down from 447,788 in 2005.

The National Archives operates 12 presidential libraries, one for every president dating to Herbert Hoover. A 13th is being built in Dallas for George W. Bush. They are funded as public-private partnerships. The Lincoln complex is operated by the state of Illinois and is not a part of the federal system.

Truman's museum drew fewer visitors last year than the museum dedicated to Gerald Ford in Grand Rapids, Mich. — and only about 11,000 more visitors than Herbert Hoover's, in West Branch, Iowa, according to the National Archives data.

The Eisenhower Presidential Library and Museum in Abilene, Kan., had fewer than 100,000 visitors a year at the start of the decade; last year, that had grown to more than 177,000.